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21. A conductor XY of length L is moving parallel to a uniform magnetic field B at constant velocity v such that the end X is ahead of Y. What will be the emf induced in the conductor?


22. Two identical loops, one of copper and other of aluminum, are rotated with the same speed in the same magnetic field. The currents induced in the loops are 1 A and 2 A. Which of the loops is made of copper?


23. A cylindrical bar magnet is kept along the axis of a circular loop. Will there be an induced current in the loop if the magnet is rotated about its axis?


24. A cylindrical ebonite rod of length L moves with velocity v in a uniform magnetic field B such that the length is perpendicular to the magnetic field. What will be motional emf in the rod?


25. A car is moving with a uniform speed from west to east. Will an emf be induced across the ends of the axle of the car?


26. A conducting rod PQ lying parallel to y-axis starts moving in z direction at constant speed in a uniform magnetic field pointing in the positive x direction. Which end of the rod gets negatively charged?


27. One end of a bar magnet is moved towards a copper ring suspended by a thread in vertical plane along its axis. Will there be any change in the position of the ring due to the motion of the magnet?


28. A pendulum with a metallic bob is oscillating in a room where the air friction is negligible. If a magnetic field is switched on in the room, what will happen to the oscillations of the pendulum?


29. A metallic ball is dropped into the space between the poles of a strong electromagnet. When the magnet is switched on, the ball falls as if it is passing through a very viscous liquid. Explain why?


30. What is an ideal inductor?


31. The time taken by the current in a series RL circuit to reach a final value depends on the inductor, but it has no effect on the final value of the current. Explain.


32. A bulb is connected in series with a battery and a coil having large number of turns. Explain why the bulb does not glow with full brightness instantly when the circuit is switched on.


33. Inductive coils are generally made of copper. Explain why?


34. What is the effect of mutual inductance on the coils between which it exists?


35. Discuss the change in mutual inductance of two coplanar, concentric coils when:
    1. the distance between the coils is increased.
    2. the number of turns in each coil is decreased.
    3. a thin iron sheet is placed between the two coils, other factors remaining the same. Justify your answer in each case.


36. Compare self-induction and mutual induction.


37. An air-core solenoid and a bulb are connected to a dc source. How does the brightness of the bulb change when an iron rod is inserted into the solenoid?


38. When we insert a soft iron rod into a current carrying solenoid, it is pulled inside by the solenoid itself. Explain why?


39. Mention factors upon which the magnitude of induced emf in a coil rotating in magnetic field depends?


40. If the speed of rotation of the armature of a generator is increased, how would it affect: (i) the maximum emf produced (ii) the frequency of the emf?

CBSE Electromagnetic Induction ( With Hint / Solution)
Class XII (By Mr. Ashis Kumar Satapathy)
email - [email protected]

Electromagnetic Induction